Fuel supply system



Dec. 29, 1959 F. C. REGGIO 2,918,912

FUEL SUPPLY SYSTEM Original Filed Feb. 3, 1939 r ufff Z 45 l///// FUELSUPPLY SYSTEM l Ferdinando Carlo Reggio, Norwalk, Conn.

Application July 27, 1943, Serial No. 496,296, which is a continuationof application Serial No. 254,355, Fel)- ruary 3, 1939. Divided and thisapplication June 7, 1956, Serial No. 589,977

The present application is a division of my application Serial No.496,296 filed Iuly 27, 1943, which is a continuation of applicationSerial No. 254,355 tiled February 3, '1939, both now abandoned.

This invention relates to fuel supply systems for internal combustionengines and in particular to mechanisms for the control of the relativeproportion of fuel and air composing the combustible mixture of internalcombustion engines. It is chiefly, although not exclusively, applicableto spark-ignition aircraft engines including a fuel injection systemdischarging liquid fuel into the engine cylinders or the engineinduction manifold.

Spark-ignition engines having a fuel injection system are usuallyprovided with means for' controlling the fuel supply and means forcontrolling the air supply of the engine. lt is important that theadjustment of the fuel and air control means be inter-related so thatthe engine cylinders may be charged with a combustible mixture having asuitable fuel-air ratio. Extensive experimental workconnected inparticular with the developmenty of aircraft engines has shown that themost suitable value of fuel-air ratio varies with the engine operatingconditions such as, for example, the air pressure or density in theinduction manifold. The fuel-air ratio corresponding to best economyoperation, required for instance in a cruising airplane, is differentfrom that corresponding to maximum power operation which is necessaryfor take-off. It is therefore advantageous that, while the means forcontrolling the engine supply of one of the components of thecombustible mixture (either the air or the fuel) may be directlyactuated by the operator, the supply of the other component may becontrolled by automatic means so as to produce the desired fuel-airratio.

One of the objects of the present invention is to provide, incombination with an internal combustion engine including fuel meteringmeans, control means whereby the fuel-air ratio of the combustiblemixture may be automatically regulated as a function of certain engineoperating conditions such as the induction air density.

Another object is to provide, in combination with a spark-ignitionengine having a fuel injection system, automatic devices for controllingthe engine fuel supply, including mixture control means whereby thefuel-air ratio of the combustible mixture is determined by theadjustment of said mixture control means and for a given adjustmentthereof is substantially independent of the en,-

The mixture control means United States Patent ice by specific names forconvenience, but they are intended to be as generic in the applicationas the art will permit.

In the drawings: Figure 1 is a sectional elevation of a fuel meteringpump; Figure 2, in part a section along line 2-2 of Figure l, shows twofuel metering pump units together with means for feeding fuel atvariable pressure thereto; Figure 3 diagrammatically indicates a fuelmetering pump applied to a radial aircraft engine and control meanstherefor; Figure 4 shows a modification ofthe fuel pressure regulatingmeans of Figure 2; and Figure 5 diagrammatically illustrates meansresponsive to the air induction system pressure or density forregulating the engine fuel supply.

As shown in Figure 1, a fuel pump 1 has a plunger 2 reciprocating in abarrel 3 having a port 5. At its upper end, beyond an annular groove 6,the plunger 2 has edges 7, 3 which limit the plunger surface in contactwith the bore of the barrel 3. Below the groove 6 and at suitabledistance therefrom, plunger 1 has a splined portion 10 formed as apinion and meshing with a rack 11 formed in a piston 12 slidable in abore 15 of the barrel 3. The lower end of the plunger 2 is urged by aspring 16 against a lifter 1S operated by a cam 19 driven by the engine.A cup-shaped cap 20 screwed on the upper end of the barrel 3 closes thepumping chamber 22 and provides, between barrel and cap, an annularchamber or reservoir 24 communicating through port 5 with the pumpingchamber 22 and through annular apertures of very small area providedbetween barrel 3 and cap 20 with the annular chambers 26 and 27. Agasket 21 prevents fuel leakage between barrel 3 and cap 20.

The annular chambers 26 and 27 communicate with a chamber 28 at one endof the bore 15 by means of ducts 3Q, 31, 32 and 33. The chamber 29 atthe opposite end of the bore 15 communicates with the reservoir 24through the duct 35. At the upper end of the pumping chamber 22 aspring-loaded check valve 36 admits fuel, through duct 38, annulargroove 39, duct 40 and hollow fastening bolt 41, to a conduit 42 leadingto the nozzle. A spring 44 acting on the piston 12 is provided in thechamber 28. In the preferred embodiment, a multicylinder engine has anumber of pumps 1, each arranged near the corresponding cylinder. Asindicated in Figure 2, a fuel transfer pump 48, connected through a pipe51 with a fuel tank, not shown, delivers fuel to a conduit 45 whichcommunicates, through a hollow bolt similar to bolt 41 and a duct 47,with chamber 29 and reservoir 2,4 of each pump 1, while chamber 28 ofeach pump communicates, through a duct 33 and another hollow bolt, witha fuel return line 49 and a pipe 50 leading fuel back to the tank.Between outlet and inlet ports of the transfer pump 48 a bypass isprovided, controlled byL a pressure regulating valve including a piston52 biased by a spring 53 whose load may be varied by screwing orunscrewing the threaded cap 54 provided with a lever arm 55. A groove 56and a duct 57 lead fuel leakage back to the return line 49.

As the delivery of the transfer pump 48 is substantially larger than thetotal requirement of pumps 1 under all operating conditions, excess fuelHows past the regulating valve 52, and the fuel pressure in the feedline 45 and in the chambers 29 of the pumps 1 will therefore becontrolled by the load of the spring 53 and the adjustment of lever 55.Changes of pressure in the chamber 29 axially displace the piston 12 andvary the angular adjustment of the plunger 2.

air charge. A second control lever 66 adjusts the angular position ofthe lever 55 shown in detail in Figure 2. The fuel conduit 42communicates with the nozzle 70 through which fuel is injected into thepipe 62 during part of the suction stroke of the cylinder 69. The nozzleitl may obviously be mounted in any other suitable position, such asnear the intake cylinder port or valve, or inside the cylinder.

In the position shown in Figure l, the plunger 2 is at the end of itssuction stroke and has uncovered the port 5 allowing fuel to ow into thepumping space 22. As the plunger rises, operated by the cam 19, thesurface comprised between the edges 7 and 8 covers the port 5. Thepressure rises rapidly in the space 22 and lifts the check valve 36, andthrough the nozzle 70 fuel is injected in the induction pipe 62 andcarried by the incoming air into the cylinder 60. The injectioncontinues until the edge 8 uncovers the port 5 which now functions as apressure relief port through which the remaining fuel displaced by theplunger is bypassed into the reservoir 24.

While the engine is in operation, the fuel pressure in the grooves 26and 27, substantially the same as in chamber 23 and fuel return line 49,is lower than in the reservoir 24, and a continuous flow of fuel isvented through the annular apertures of very small area provided betweenthe reservoir 24 and the grooves 26 and 27. The volume flowing throughan orifice under a given difference of pressure being for a gas or avapor several times larger than for a liquid, the area of said aperturesmay be made such that under the existing difference of pressure, vaporor gas separating from the fuel in the reservoir 24 can be eliminatedtherefrom, while only a relatively small volume of liquid fuel escapesthrough said apertures. As said annular apertures surround the port 5',whatever the orientation of the pump i may be relative to the verticalline, gas or vapor bubbles can be vented from the reservoir 24 at somepoint higher than the port 5, thereby reducing the risk of such bubblesbeing drawn into the pumping space 22 where they might interfere withthe correct operation of the pump.

The plunger 2 being provided with at least one substantially helicalcontrol edge, the duration of its effective delivery stroke and therebythe Weight of fuel delivered per stroke may be varied by a turningadjustment of the plunger obtained by adjusting the fuel pressureregulating valve 55. ln the preferred embodiment of the invention thefuel supply system is so arranged that changes in fuel pressure in theconduit 45 and the corresponding variations in the delivery per cycle ofthe pumps i are proportional. Owing to the fact that the axialdisplacement of the valve piston 52 corresponding to changes in the fuelflow through the valve is very small and the spring 53 is very flexible,changes in the load of the latter due to said axial displacement of thepiston 52 are practicaliy negligible, the variations of angularadjustment of the lever 55 and the corresponding changes of fueldelivery per cycle of the pumps l may also be considered proportional.To secure proper venting and cooling of the pumps i under allconditions, it is advisable that the zero delivery angular adjustment ofthe plunger 2 correspond to a predetermined pressure in the feed line 45higher than in the fuel return line 49. Figure 4 indicates analternative form of pressure regulating valve wherein a highly resilientspring 73 is adjusted to exert ou a valve piston '72 a load whichbalances said predetermined fuel pressure that corresponds to said zerodelivery angui ar adjustment of the plunger 2. Since, as previouslyStated, the maximum axial displacement of the Valve piston 72, underextreme operating values of fuel flow through the port controlled by thepiston 72, is very small and the spring 73 is very flexible, if no loadis applied to the outer end of the piston 72, the fuel pressure in theconduit 45 is maintained by the spring 73 substantially constant at saidpredetermined value independently of changes of delivery of the fueltransfer pump 48, and the plungers 2 are maintained angularly adjustedfor zero delivery. If a further load is applied to the valve piston 72,for instance by means of the lever 74, the fuel pressure in conduit 45is increased beyond said predetermined value and the plungers 2 areturned to deliver to corresponding quantity of fuel. Hence in thepreferred embodiment of the invention, as already pointed out, the fueldelivery per cycle of the pumps 1 is proportional to the loadtransmitted to the piston valve 72 by the lever 74.

One of the advantage of this fuel supply system is that control of fueldelivery is obtained by adjusting the pressure regulating valve, whichmay be performed by automatic devices of very little energy, especiallyif compared with' fuel pumps of the same general characteristics inwhich turning adjustment of the pump plunger is obtained by means oflinks positively inter-connecting all plungers with the control means,whereby if a plunger is scored and cannot be turned in its barrel, itmay prevent the adjustment of all other pump plungers and put theengines out of control. in the fuel supply system which is hereindescribed, a failure occurring to one pump does not interfere with theoperation of the other pumps.

The arrangement of Figure 3 in which the air and fuel supplies arecontrolled by distinct levers 65, 66 is not suitable for spark-ignitionengines, which require a combustible mixture having definite fuel-airratio. According to the invention, a more convenient arrangement, shownin Figure 5, includes pressure responsive means, such as a resilient andevacuated bellows 75 surrounded by fluid having the same pressure as inthe induction pipe 62, transmitting to a fuel pressure regulating valve72, through a link 76 and a lever 74, a load proportional to theinduction pressure. The operating distance of link 76 from the fulcrumof lever 74 may be varied by lever 79 connected with the control lever'78 whereby the ratio of fuel delivered per cycle to induction pressuredepends on the adjustment of the control lever 78 and is independent ofengine operating conditions or altitude. This simple device, applied toan internal combustion engine in which the induction temperature, ortemperature of the air in the engine manifold 62, is substantiallyconstant, as may be the case where an intercooler is used and in whichthe cylinder air charge is proportional to the induction pressure,automatically controls the fuel delivery so as to maintain, for eachadjustment of lever 78, a corresponding constant value of fuel-air ratioin the combustible mixture. This device is intended to be used incombination with means for controlling the air supply of the engine,such as for instance that indicated by numerals 63 to 65 in Figure 3, bywhich the induction pressure in manifold 62 may be regulated. The maincontrol of the engine is throttle lever 65, and the fuelair ratio may beadjusted by the mixture lever 78. In combination with engines in whichthe variations in induction temperature are small but not negligible, itmay be convenient in order to compensate for variations in air densityand engine air supply due to small changes of temperature in manifold62, to provide in the bellows 75 a certain weight of fluid, the pressureto which increases with the temperature, the arrangement being such thatthe temperature of the bellows 75 be the same as in the pipe 62 whereby,for a given pressure in said pipe, the fuel delivery is reduced when theinduction temperature increases and the density of the air in themanifold 62 correspondingly decreases.

As shown in Figure 5, the bellows 75 is enclosed in a housing WhoseWalls are preferably heat-insulated, connected with the induction pipe62 by means of a large and short conduit. Eddy currents or turbulence insaid conduit and housing caused by the high velocity of the air ow inthe pipe 62 as well as the pulsations of pressure therein, produce anactive thermic exchange, by conduction and convection, between the airflowing in pipe 62 and bellows 75. The thermal capacity of such bellowsusually is, or may be made, extremely small. Hence, as previouslypointed out, the air flowing through the pipe 62 and the expansiblefluid within the bellows 75 will have substantially the sametemperature.

It is to be expressly understood that the invention is not limited tothe specific embodiments shown, but may be used in various other ways,and changes, modifications, substitutions, additions and omissions maybe made in the construction, arrangement and manner of operation of theparts without departing from the limits or scope of the invention 'asdefined in the following claims. Where the claims are directed to lessthan all of the elements of the complete system disclosed, they areintended to cover possible uses of the recited elements in installationswhich may lack the non-recited elements.

I claim:

l. In a multi-cylinder fuel injection engine having a supercharger, anair entrance leading thereto, a throttle in said entrance, air exitsleading from said supercharger to said cylinders, engine operatedmetering fuel pumps adapted to discharge fuel charges for each cylinder,a fuel supply pump adapted to deliver fuel under a variable fuelpressure to all of said metering fuel pumps, mechanical means forvarying the quantity discharged by each individual fuel pump responsiveto said variable fuel pressure, control means for regulating saidvariable fuel pressure responsive to the pressure created by saidsupercharger.

2. A supercharged engine having fuel injection units, fluid pressureactuated delivery control means in each of said units, a source ofpressure fluid, conduit means connecting said source and units, andsupercharged air pressure responsive means for controlling the fluidpressure actuating said delivery control means.

3. A supercharged engine having fuel supply units, fuel pressureactuated delivery control means in said units, a source of pressurefuel, conduit means connecting said units with said source, and enginesupercharged air pressure responsive means for controlling the fuelpressure actuating said delivery control means.

4. A multicylinder engine having fuel supply units,

`each of said units intermittently supplying pressure fuel to acorresponding engine cylinder, individual fluid pressure actuateddelivery control means for each of said units, fluid conduit meansconnecting said control means, and engine induction air pressureresponsive means for controlling said fluid pressure.

5- An engine having individually fluid pressure controlled fuelinjection units, a valve for regulating the fluid pressure controllingsaid units, said valve being subject to the same fluid pressure, andengine manifold air pressure responsive means for exerting an operativeload on said valve against said fluid pressure.

6. An engin: having individually fluid pressure controlled fuel supplyunits, valve means for regulating the fluid pressure controlling saidunits, said Valve means being exposed to said fluid pressure, and enginemanifold air pressure and temperature responsive means for actuatingsaid valve means against said fluid pressure.

7. An engine fuel supply' system including individually fluid pressurecontrolled injection'units, valve means for regulating the fluidpressure controlling said units, said valve means being subject to thesame fluid pressure, means for applying an operative load proportionalto the engine induction air pressure to said Valve means against saidfluid pressure, and means for varying the ratio between said inductionair pressure and said load.

8. A fuel injection system for radial engines including individuallyinterchangeable injection units.; each of said units having a radiallyarranged plunger reciprocable from a common engine-driven cam coaxialwith the engine shaft; variable pressure fluid containing means anddelivery control means operated by the fluid pressure therein; a sourceof pressure fluid, conduitA means for interconnecting said source andcontaining means, valve means for regulating the pressure in said fluidcontaining means, and means responsive to engine induction air pressurefor actuating said valve means.

Y 9. For use with an engine having a fuel injection system including atleast one injection pump; plunger means in said pump; means in said pumpfor imparting reciprocatory motion to said plunger means; conduit meansin said pump for the discharge of high pressure fuel displaced by saidplunger means; fuel inlet means in said pump for admitting comparativelylow pressure fuel to said pump; variable-pressure fuel containing meansconnected with said fuel inlet-means; and resiliently loaded slidablecontrol means in said pump actuated upon changes of pressure in saidfuel containing means for varying the effective stroke of said plungermeans whereby the rate of fuel discharge of the pump varies with thepressure in said fuel containing means: a fuel metering device includingslide valve means whose adjustment affects the fuel pressure in saidfuel containing means; duct means through which flows engine intake air;and pressure and temperature responsive means connected with said ductmeans for actuating said slide valve means.

10. Engine fuel supply system comprising a fuel'control unit forcontrolling a fuel injection pump of the type including: plunger means,tappet and spring means for imparting reciprocating motion of constantstroke to the plunger means, conduit means for the intermittentdischarge of high pressure fuel displaced by the plunger means, fuelinlet means for admitting low pressure fuel to said pump, and springloaded slidable control means which move upon changes of fuel pressurein said fuel inlet means to vary the effective stroke of the plungermeans whereby the rateof fuel supply of the pump varies as apredetermined function of the fuel pressure in said fuel inlet means;said fuel control unit including: fuel duct means connected with thefuel inlet means of said pump upstream withrespect thereto, orificemeans in said duct means, slidable valve means controlling the orificemeans, the adjustment of said valve means being affected by fuelpressure variations in said duct means, the adjustment of the same valvemeans in turn affecting the fuel pressure in the fuel inlet means ofsaid pump, and pressure and temperature responsive means connected withan element of the engine intake air system for actuating said valvemeans.

l1. For use with an engine having an air induction system; at least onepump driven from the engine; plunger means in said pump; means forimparting reciprocating motion to said plunger means; conduit and nozzlemeans for the discharge of high pressure fuel displaced by said plungermeans; fuel inlet means in said pump for admitting low pressure fuelthereto; resiliently loaded control means actuated upon changes of fuelpressure in said fuel lnlet means for varying the effective stroke ofthe plunger means; and fuel metering means including fuel duct meansconnected with the fuel inlet means of said pump; orifice means in saidduct means; a valve for controlling said orifice meansto cause pressurevariations in the fuel inlet means of said pump; and air temperature andpressure responsive means connected with said air induction system foractuating said valve.

12. In a fuel system for an internal combustion engine: a fuel supplypump; a connection for conducting fuel from the pump to the engine;means includinga pumping member driven by the engine for delivering fuelto the engine; means for varying the fuel flow to the engine; apassageway for transmitting a Variable fuel control pressure created bythe first mentioned means to the varying means; andA engine inductionpressure responsive means for varying the control pressure. ,-13. Foruse with an engine and a fuel-supply pump driven from the engine, a fuelsystem comprising aconduit adapted to connect the pump with the engine;means for creating a fuel pressure in and effecting a flow of fuelthrough said conduit means for controlling said flow; means adapted tocontain a control pressure developed by the first mentioned means andacting on the second mentioned means for influencing the functioningthereof; and air pressure and temperature responsive means and manuallycontrolled means for varying the control pressure.

14. ln a fuel system for an internal combustion engine: a source offuel; a conduit connecting said fuel source with the engine; means forcreating a fuel pressure in and effecting a flow of fuel through saidconduit; means for controlling said flow; means adapted to contain acontrol pressure developed 'oy the first mentioned means and acting onthe second mentioned means for influencing the functioning thereof; andtemperature responsive means for varying the quantity of fuel suppliedto the engine.

l5. The invention defined by claim 14 and including a manuallycontrolled valve for modifying the control pressure.

16. For use with an engine having an air induction System, a fuel supplypump, and an injection pump having fuel delivery control means and fuelpressure responsive means connected with said pump for actuating saidcontrol means to vary the fuel delivery as a predetermined function ofthe fuel pressure on said pressure responsive means; valve means forvariably regulating said fuel pressure, and means responsive to airinduction pressure and temperature for actuating said valve means.

i7. For use with an engine having an induction system, a source ofpressure fuel, and an injection pump including delivery control meansand fuel pressure responsive means for sensing pressure variations inthe fuel supplied to the pump and actuating said control means to varythe fuel delivery of the pump in predetermined relation to said fuelpressure; a control device including: conduit means for leading fuelfrom the source to the injection pump; valve means connected with saidconduit means; and manually operable control means and induction airpressure and temperature responsive means for positioning said valvemeans.

18. ln a fuel control for an internal combustion engine having an airpassage, a fuel conduit, a fuel injection pump for receiving fuel fromthe conduit and delivering it to the engine, servo-motor actuated meansfor controlling the effective stroke of the pump to thereby control theflow through the fuel conduit, and means responsive to the resultant ofopposed forces created by air and fuel pressures for controlling theservo-motor.

19. ln a fuel injection system for an engine, a fuel injection pump, afuel conduit leading from the pump to a cylinder of the engne forsupplying individual charges of liquid fuel thereto in timed relationwith the engine, a fuel control element for varying the quantity of fuelin the individual charges, a fuel passage for supplying fuel to thepump, an air passage for supplying air to the cylinder, a control elenent for vary'ng the quantity of air supplied to the cylinder, pressurefluid means actuating said fuel control element and means responsive toair and fuel pressures for controlling said pressure fluid means.

20. ln a charge t forming device, a fuel injection pump, an air passage,a first element controlling the effective pumping capacity of the pump,a second element controlling tne air passage, means for manuallyactuating said second element, a movable pressure responsive member foractuating said rst element, means for subjecting the member to fuelpressure, and means responsive to air and fuel pressures for varying thefuel pressure on the member to control said first element.

21. in a fuel injection system for an engine, a fuel injection pump, afuel conduit leading from the pump to @l a cylinder of the engine forsupplying individual charges of liquid fuel thereto in timed relationwith the engine, a fuel control element for varying the quantity of fuelin the individual charges, an air passage for supplying air to thecylinder, an air control element for varying the quantity of airsupplied to the cylinder, manual means for actuating said air controlelement, a movable pressure responsive wall operatively connected to thefuel control element, means including a fuel conduit for supplying fuelto the pump and the wall, and means responsive to air and fuel pressuresfor varying the pressure of the fuel on said wall for operating the fuelcontrol element.

22. in combination with an engine having an air-intake conduit providedwith a throttle and fuel supply means having an output proportional toengine speed and whose output at any given speed is variable, a membermovable to control the output of said fuel supply means, automaticfuel-air ratio controlling mechanism functioning to vary the admissionof fuel to said fuel supply means to obtain predetermined fuel-airratios for all operating positions of the throttle, and a movableelement operatively connected to said member and subjected directly tothe fuel admitted to said fuel supply means for regulating the effectivedelivery of said fuel supply means in response to variations in thepressure of said fuel.

23, ln a fuel mixture control for an internal combustion engine, an airpassage, a fuel conduit, a throttle for controlling the flow through theair passage, a servomotor actuated means for controlling the llo-wthrough the fuel conduit, and means responsive to the resultant ofopposed forces created by air and fuel pressures for controlling theservo-motor.

24. In a fuel injection system for internal combustion engines of thetype comprising a charge pump driven by the engine and supplying fuel tothe engine and a feed pump driven by the engine for supplying fuel tothe charge pump, a fuel metering valve disposed between the charge andfeed pumps for varying the amount of fuel delivered to the charge pumpand thereby controlling the speed of the engine comprising a body havinga passageway communicating with each of the pumps, a valve membermovable endwise for progressively increasing and decreasing the fuelflow through the passageway depending upon the position of the valvemember, said valve member having an end surface subjected to thepressure of fuel in the passageway, a spring seat slidably mounted formovement toward and away from the valve member, a spring between thevalve seat and the valve member opposing movement of the valve inresponse to said pressure, and means for variously positioning the valvemember in said passageway comprising means for moving the spring seat.

25. in a fuel injection system for internal combustion engines of thetype comprising a charge pump driven by the engine and supplying fuel tothe engine and a feed pump driven by the engine for supplying fuel tothe charge pump, a fuel metering valve disposed between the charge andfeed pumps for controlling the speed of the engine comprising a bodyhaving a passageway communieating with each of the pumps, a valve membermovable endwise and connected with said passageway for progressivelyincreasing and decreasing the fuel flow through the passageway dependingupon the position of the valve member, said valve member having an endsurface subject to the pressure of fuel in the passageway, a spring seatslidably mounted for movement toward and away from the valve member, aspring between the valve seat and the valve member opposing movement ofthe valve in response to said pressure, and means for variouslypositioning the valve member in said passageway comprising actuatingmeans extending transversely of the passageway and operable from theexterior of the valve for moving the spring seat.

26. In a fuel injection system for internal combustion engines, a chargepump driven by the engine and supplying fuel to the engine cylinders, afeed pump driven by the engine for supplying fuel to the charge pumpunder pressure responsive to engine speed, means forming a feedpassageway between the feed pump and charge pump, a movable valveoperatively associated with the passageway for varying the fuel flow inthe passageway and having a surface subjected to the pressure of fuelment of the valve responsive to fuel pressure, and means movablerelative to the valve for adjusting the force of 5 the spring.

No references cited.

